Kinesin and myosin are the founding members of two distinct superfamilies of proteins responsible for motility. While members of both protein families generate force and are responsible for producing motion, they show no detectable equence homology. Unexpectedly, the crystal structures of both myosin and kinesin are homologous to one another, indicating that they share a common mechanism of ATP hydrolysis and possibly a common mechanism of force generation. By comparison of the two structures, we have determined the homologous regions of the two proteins. Comparison of the homologous regions with the large numbers of known kinesin and myosin structures has enabled us to determine the crucial residues in the conserved regions. We are currently examining the possible functions of these residues in combination with molecular modeling at the Computer Graphics Laboratory. An additional goal of this project is to search for other potential motors which share the kinesin/myosin fold. We have approached this by searching Genbank for sequences which match either a fingerprint determined from the conserved regions, or which match a profile determined from the conserved regions. This work is still underway.